2010 April/May

 EDITORIAL ...... 2

 BLACK HOLES,THE HIGGS PARTICLE AND CERN ...... 3

 HOUSTON ASTRONOMICAL SOCIETY 8 Sky

 TELESCOPES FOR LOAN 12

 SOCIETY NOTICES ...... 14

watcher  TRAINING COURSES .... 14 April/May 2010

 LATEST ON THE NEW OBSERVATORY 15

 NIGHT SKY FOR APRIL . 17

 NIGHT SKY FOR MAY .. 18

 WHAT’S ON APRIL/MAY 19

 THE REALM OF THE GALAXIES 20

This months cartoon courtesy of www.xkcd.com

Hi everyone,

I hope you‟ve all now recovered from the clocks being bumped forward last weekend. On one hand I like the fact that I now get to go home in daylight, but the knock-on effect of the sudden decrease in my pre-midnight observing time always comes as a bit of a shock. Not that I‟ve actually done much observing this month, but that‟s another story.

In this issue of Skywatcher we have I think, something for everyone. Mark Eaton takes us on a trip around the Large Hadron Collider, which I picked up on as I was tuned to Radio 4 earlier this week on the evening commute. It seems the initial results are in and it‟s working just fine. Given the bil- lions it cost I imagine that all concerned are just plain relieved, and the team now has a „go‟ for running it at full-power. Mark‟s article is a great read for the armchair cosmologists or particle physicists amongst you and prepares the way for interpreting the results.

On a completely different note, one of our long-standing members and a past-President from long ago: Brian Gordon-States, has a piece on our twinned society - Houston Astronomical Society. Per- sonally, I‟m always interested to read about what other Societies are up to and what facilities they offer to their members. I‟ll let you read and make up your own mind, but I‟m not giving too much away if I mention that you might like to compare their observatory site with ours.

On that particular topic, as we feature some late-breaking pictures from the latest work-party that has been hard at work on the new observatory building up at Holmbury. When all the hard work is com- plete and it‟s fully-operational, this promises to revolutionise (an abused word undoubtedly, but en- tirely justified here) our observing activities as we will have an excellent imaging facility for members to use. However, the JST (John Smith Telescope) is not to be retired and will continue to be available to members – the opportunity to do some visual observing with a 20-inch telescope is not to be ignored.

As a neat and unintentional segue into visual observing, we round things off with a short article courtesy of your truly on the Virgo Cluster of galaxies. Pitched at owners of small(er) telescopes or large binoculars, it‟s (hopefully) a useful guided tour around the cluster taking in most of the Messier and some bright NGC objects on the way. April is perhaps the best month in the year to do this as the cluster is high in the south, and it‟s before the summer twilight starts interfering too much. Getting some experience of finding your way around what is a challenging area of the sky paves the way for using the JST. Whereas you may see a few galaxies in the same field with a small telescope; seeing a dozen or so in the same field with the JST is simply an unforgettable observing experience.

So happy reading and hope to see you under the stars at one of our observing evenings.

Peter Dean, Editor [email protected]

If you would like to contribute an article or other item to Skywatcher, I will be very pleased to in- clude it. Articles can be any length and images are most welcome, so long as they are yours. You can send them via email to the address above. I‟m always open to suggestions for ways of improving the magazine, so please feel free to send me any feedback to the same address. Alternatively, start a dis- cussion on the Society Bulletin Board.

Page 2 © copyright 2010 guildford astronomical society www.guildfordas.org Black Holes, The Higgs Particle and CERN What’s the connection between the Eiffel Tower, Star Trek, Margaret Thatcher and the Higgs Particle? Read on to find out as Mark Eaton takes us on a behind-the-scenes visit to the LHC at CERN

onsidering that the Large Particle, CERN has already gener- Hadron Collider (LHC) at ated a number of Nobel prize win- CERN in Geneva is look- ning discoveries and such things as C ing at some of the small- World Wide Web. The site is home est particles in the universe, the to around 10,000 people, including numbers associated with it are truly some 2,500 staff and researchers as „astronomical‟. It has never failed to well as students and researchers amaze me how sub-atomic particles from the nations who support the can teach us so much about the big- facility. It is fully equipped with its gest issues in astronomy and cos- own travel agency, post office and mology such as dark matter and the shops and the roads are all named Big Bang. after famous scientists.

As a mature student of astrophysics I was able to visit CERN through the International Association of Physics Students (IAPS) (http:// www.iaps.info/) and we were able to access some of the latest thinking at the world‟s biggest experimental site as well as visiting some of the facilities surrounding the LHC. The Large Hadron Collider itself is One immediate thing that hit me was obviously the centrepiece of the fa- the age of the site. CERN has been cility, although you would be hard hitting the news for over 50 years pressed to spot it even at 27km long and whilst most people in the world as it is located 100m underground, know about the search for the Higgs with the majority of it residing in France (where it is easier to buy land). The LHC itself consists of over 9,000 magnets designed to steer two proton „beams‟ (more accurately packets) around the 27km circuit. The beams are then converged at four experimental points called AT- LAS, ALICE, CMS and LHCb, or they can be sent toward a fixed tar- get. Each of the experiments are huge. One, the CMS (Compact Muon Solenoid,) contains more metal than the Eiffel Tower and weighs 12,000 tonnes and each of the four experiments have their own control room.

A sculpture in the CERN reception that reacts to Cosmic Rays hitting it Protons collided in the LHC are trav- with random patterns of light. elling at 99.9999% of the speed of (Continued on page 4)

(Continued from page 3) light and they impact with a combined power of 14TeV (Terra Electron Volts) (this is 14,000,000,000,000 Electron Volts where 1 Electron Volt is the kinetic energy gained by an electron when it The CMS (Compact Muon Solenoid) Control Room. is accelerated by a bat- The LHC has four main experiments (Atlas, Alice, tery power of 1 volt). CMS and LHCb) and each has its own control room. For reference the power given to an electron in the that on an observing night!) with a cathode ray tubes that used to be resolution of 75 megapixels. More popular in TVs is given only than that, it can take 40 million 20,000 electron volts, so interac- pictures per second of proton im- tions within the LHC are some pacts when it is running and this is 700 million times more powerful. more data than could ever be The CMS has a stored so they have to quickly camera with a sur- The particles in the LHC are re- screen the image and decide 2 ferred to as a beam but in reality whether to keep it or discard it. face area of 220m they travel around the system in This reduces the number of frames with a resolution of „packets‟, each containing 1011 taken when the machine is running 75 megapixels. protons. When the LHC is running to around 100 per second. it has a total of 2808 „packets‟ of More than that it protons, each located 7.5m apart Much has been written about the can take 40 million as they travel around the 27km. possibility of the LHC producing a pictures per second These packets are brought to four „micro-Black Hole‟. In reality this collision points within each of the is a distinct possibility they told four experiments producing us, but given that the Black Hole 6.5x108 proton-proton collisions created will evaporate in one mil- every second whilst running. lion million million millionth of a However, the LHC is only the end of the proton‟s journey as it first has to be accelerated by three smaller systems that raise the speed of the proton from a few metres per second to 87% of the speed of light (261,000km per second) before being injected into the LHC.

The amount of data col- Dr Rolf Landua – a leading particle physicist who ad- lected by the LHC experi- vised the cast and director of the film ‘Angels & De- ments is truly vast. The mons’ and tried to reduce the number of factual sci- CMS alone has a camera entific inaccuracies – he admits he was not com- with a surface area of pletely successful. 2 220m (imagine carrying (Continued on page 5)

www.guildfordas.org

(Continued from page 4) threatened by a bomb containing a second (10-24) through „Hawking „highly combustible‟ material Radiation‟ it is unlikely to be a big called antimatter for which they issue. What‟s more is that the colli- have around a half a kilo. Firstly, sions going on at the LHC have antimatter does not combust it just been occurring naturally in the up- converts normal matter into energy per atmosphere at the rate of and also the time required to pro- 100,000 per second for 4.5 billion duce half a kilo of antimatter would years and therefore if a serious need the LHC (working at full pelt) black hole were to be created it to be running continually for would probably have already oc- around 10 billion years. Apart from curred. So no need to worry in the this the physicists also destroyed next few weeks! my faith in the availability of matter transporters and warp drives One thing that they do find regu- from Star Trek anytime soon (or larly at CERN is antimatter. Indeed, ever!) for every million protons pro- This is the dipole test facility. The LHC has in excess of 2,000 Dipoles duced they identify one anti- It is a shame that we could not go and a further 9,000 magnets through- proton. The team at CERN pro- down into the tunnels to see the out its 27km circumference. vided advice to the producers of LHC but given that they are cooled the film „Angels & De- by liquid Helium at a temperature mons‟ (based on the Dan Brown of 1.9 Kelvin (-269 degrees C) and the physicists book of the same name). Ron How- that if it warms up by only 1 or 2 also destroyed ard, the director of the film was degrees it will expand 800 times keen to reduce many of the scien- (meaning that anyone in the tunnels my faith in the tific errors that apparently were in will speak with a high pitch voice availability of the book so wanted some real sci- for a few seconds and then drop mattertransporters entific advice. However, not all of dead). What is even more impres- the inaccuracies could be elimi- sive is the temperatures that they and warp drives nated and in the film the Vatican is can achieve in the impacts (1015 K from Star Trek anytime soon

The Low Energy Ion Ring (LEIR). Part of the LHC ‘system’ that actually includes five accelerators and many different experiments. This is being converted so that it can ‘slow down’ Lead particles. (Continued on page 6)

The structure of the accelerators at CERN. (Continued from page 5) – that‟s 1,000,000,000,000,000 mass of the universe. degrees), the fact that they have a vacuum that contains even fewer 26% of the rest of the mass is felt particles than outer space and the to be Dark Matter which is mate- ability of the LHC to recreate tem- rial that does not emit electromag- peratures and energy levels not netic radiation (including visible seen since one billionth of a sec- light) but that does interact gravita- ond after the Big Bang. tionally with ordinary matter. It is the halo of Dark Matter that is felt Is all this money relevant? If we to enable spiral galaxies to main- forget the fact that understanding tain their „arms‟ for extended peri- how atoms work will help us to ods rather than simply falling understand the universe more com- apart. 70% of the mass is in the pletely, the applications of particle form of Dark Energy which at its physics have found their way into simplest level is felt to be the force medical applications such as PET driving the expansion of the uni- (Positron Emission Tomography) verse. and MRI Scanners whilst the needs In terms of the 4% of matter that to analyse data has given us the constitutes everything we can see world wide web and will, they be- another factor that CERN is trying lieve, in the future give us an even to understand is why the universe better system called the „Grid‟. favours matter over anti-matter. At In terms of understanding the uni- the Big Bang matter and antimatter verse more effectively one key de- particles were converting into en- velopment they hope will come ergy as they annihilated each other from the work at CERN is to un- but for 1 billiion antimatter parti- derstand more about the nature of cles there appear to have been 1 Dark Matter and Dark Energy. The billion and 1 particles of normal surprising thing about all of the matter. This 1 particle per billion things we can see in the sky is that that was „left over‟ actually consti- it accounts for only 4% of the total (Continued on page 7)

(Continued from page 6) tutes everything we are and every- 1. Imagine there is a cocktail thing we can see. party with a room full of people – This is the Higgs Field. The most interesting „matter‟ to us 2. When someone famous enters as humans is what is termed Bary- the room people flock toward onic Matter. A Hadron (as in Large them – This is the creation of Hadron Collider) is the generic a new particle. name given to any particle made of 3. The famous person tries to „Quarks‟ (of which there are six cross the room but is „slowed types). Baryons is the name given down‟ by people wanting to any particle made of 3 Quarks, autographs – This is the with Protons being made of what Higgs field giving the particle are termed 2 Up and 1 Down Quark „inertia‟. and Neutrons being made of 2 4. A rumour starts that the per- Down and 1 Up Quark. To get a sonality will make a speech – feel for the size of things for those This is the Higgs field be- of us who had a classical education coming „excited‟ and receiv- that stopped at the Proton trying to ing energy. determine the size of these particles 5. Many guests clump together is amazing. The nucleus of an atom to discuss the rumour – This (containing the protons and neu- is the creation of a real parti- Imagine there is a trons) is actually only 1/10,000th cle (the Higgs Particle) cocktail party the size of the atom and Quarks are 6. only 1/10,000th the size of a proton Of course, the Higgs particle may with a room or neutron. The amazing thing is not be real and even at best they full of people – that Quarks really don‟t want to be only expect to see it once in every this is the separated from each other which is million million collisions but as why they need to be involved in Rolf Landau (a lead figure in the Higgs Field. collisions with such high energies, search for the Higgs particle) said, and in the process they give off a “Not finding the Higgs will be even blast of other particles with strange more exciting than finding it as it names such as Muons and Gluons. will prove that our existing models of how atoms work is wrong.” Of course, discovering the Higgs Boson and the Higgs field is the priority for CERN at present. This will help us to understand more about the fundamental forces in the Universe and in particular to understand how matter has mass. To understand more about the Higgs particle and field in simple terms the physicists provided us with the briefing paper that was given to Margaret Thatcher when she was asked to help fund the development of it (yes, the LHC is that old) and it goes like this:

ouston A.S was formed in 1954, the same year as Guildford A.S. Cur- rently the Society has H(as of January 6th 2010) 273 members.

Regular meetings of H.A.S take place at the University of Houston on the first Friday of each month. It is a very active society and like us here in Guildford, is involved in outreach programmes to educate and inform the public. They also have S.I.G‟s (special interest groups)

Back in June 1987, Guildford A.S and Houston A.S were “twinned” forming links to benefit both societies, and to take advantage of the 90 deg difference in longitude. I was unknowing reader might assume in the U.S on vacation for four that it was signed on two different weeks with my family and made a occasions nearly a month apart. Of presentation at the Houston society course it is just the use of the U.S meeting on June 5th on the subject date format of month then day then of astronomy in the U.K. At the year and our U.K format of day same time Lee Cain (pictured be- then month then year. low) and I signed the official twinning charter. Of the original four copies of the twinning charter (there were two A3 and two A4) one of the A3 copies is the warm up room at the H.A.S observatory warm up room (or at least it was the last time I looked), the second A3 was is the shed at the G.A.S Observatory at Holmbury, and Peter Dean and I have the A4 originals.

Initial projects agreed on were the Reading the charter identifies one observing of variables stars, with of the few differences between us Paul Sventeck of H.A.S being an and the U.S.A. Looking at the dates avid observer of these, the only at the bottom of the charter it can problems was that no one in G.A.S be seen that Lee dated his signature was observing variable stars. Also a 6/5/87 and I dated mine 5/6/87. An (Continued on page 9)

(Continued from page 8) quirement is that observers fill in few members had articles published observing records at the end of a in each others magazines, the session and these are left in a spe- Guidestar for Houston and the Sky- cial post box for access by the own- watcher for G.A.S. I initially sub- ers. mitted articles from G.A.S as Hous- ton Coordinator, and then Peter On approaching the site during day- Dean took over. Since then nothing light hours – no one is allowed to much has happened. drive in after dark – members are confronted by a locked gate, the Back in 1987 and for a while after combination lock for which is everything was sent by snail mail changed regularly. The long low, and communication improved with observatory building dominates the the advent of the internet and e- view off the right. mail. I am regularly in contact with three members in H.A.S, and this has now grown since I signed up with their server list. I am also able to have online video chats via Skype with a three other members of H.A.S which I find very rewarding and enjoyable. The observatory has an electrically HOUSTON ASTRONOMICAL operated run on roof with automatic SOCIETY OBSERVATORY cut offs and is air conditioned.

The H.A.S Observatory site is located at Columbus 80 miles west of Houston (and some of our members complain about driving 7 or 8 miles to our site at Holmbury).

The site covers an area of 18 acres 6 of which have been cleared leaving a lot of surrounding trees to pro- tect the site. The observing site is known over there as “Padhenge” because of the Inside the observatory houses three 38 concrete pads that mem- telescopes. A 12.5” f5 Newtonian, bers us to stand their tele- C14 Celestron SCT and a 12.5” f7 scopes when observing. All Newtonian (ex NASA). Attached to PadHenge... pads are within 50 feet of the observatory is a warm up room electrical hooks ups. and there is sleeping for 6, with toi- lets (rest rooms) for both male and H.A.S has had this site free of female. This is also air conditioned. charge by the owners and only re- (Continued on page 10)

(Continued from page 9) You can spray yourself all over Dusk starts to fall and the with the ultimate mosquito repel- flying bugs and birds are lent “OFF”, but the problem is dashing around feeding on someone forgot to tell the mosqui- the early to rise mosqui- toes that they are not supposed to toes. At first one thinks of like it. Anyway, they are a minor these bugs as a nuisance, inconvenience. but later you wish they were back. Off towards the exit from the site there is a long curved line of red As darkness falls and the lights on the ground. I had encoun- eyes become dark adapted, tered these during daylight. They the eyes easily make out look like the bottom of 1 litre Coke Queuing up for food the familiar constellation bottle that have been filled with shapes, but then as full some form of resin, with a red l.e.d darkness falls, and the yes become implanted in them. These are the dark adapted, these familiar shapes only lights you have when you seem to melt into the background drive out of this site during the of a myriad of stars. hours of darkness. No late arrival or leavers here with car lights on. The It has always been humid when I car light fuses are pulled, and you have observed at Columbus, so no drive out in darkness and follow the cold weather clothing needed there. line of red LEDs. I saw what they The darkness is punctuated by the did with unwanted light pollution chirping of the cicadas (which down at the Texas Star Party at Fort sound like loud grasshoppers) and Davis in West Texas. along the tree lines here are the flashes of fireflies. The silence is The T.S.P that I attended in ‟87 was broken by the whirring of tele- great – included observing at the scopes motors, and the low mur- mur of amateur astronomers at work. More un- familiar constellations come into view, not seen from our more northern lati- Camping grounds for tents and tudes – here we R.V’s are available are 29° south and THE TEXAN ANTI-LIGHT POLLUTION DEVICE 96° west. Occa- sionally there will be a “Wow – did you see that” as a McDonald Observatory, but that is meteor flashes across the sky, more another story. murmuring then back to silence. There is another noise which I soon Back at the observing site I was came to know – the darned Texas able to stroll around many tele- mosquito. These little devils are scopes of amazing variety, up to capable of giving a real bite – 36” Dobsonians, do you fancy ob- where are those flying bugs and serving from the top of a 15 foot birds when you really need them. (Continued on page 11)

sincerely hope that many of us will, follow the following instructions.

To join the Houston A.S list, the members should send an email to: [email protected]

• In the body of the message put: subscribe haslist • i.e. subscribe haslist Joe Bloggs • Nothing is needed for the subject line. • Do not sign e-mail A busy time at the observing site for a star party, several of which are held every year. The red arrow points to a the monster tele- You should get a message back in a scope shown in the star party photo is a 36" f4.5 Dobsonian few minutes that you are now subscribed. There is a note at the bot- (Continued from page 10) tom of the e-mail that you receive ladder? As usual with amateur as- that mentions $10 – you can ignore tronomers, I was welcome to ob- this. serve through any of the scopes. The globular Omega Centauri, oh NOTE:- - please don‟t enter Joe wow, how beautiful, and the dark Bloggs – your name will do. lanes of dust in the edge on galaxy Centaurus “A”, (NGC5128) – It is If my little article has inspired you just not fair why they get all the – please also visit the H.A.S web good stuff. I could go on – but I site: http://spacsun.rice.edu/~has/ won‟t. We look forward to many of our RENEWAL OF LINKS members communicating across the big pond It has been decided by G.A.S to renew our links with H.A.S and I Pictures courtesy of Houston Astronomical Society, and Leland A Dolan. have been exchanging e-mails with them with a view to closer contact. Initially I have - with the great help of H.A.S – to sign up and access the server list which is their e-mail system in which members discuss all manner of astronomical features such as new equipment, solving problems, advising of news and events etc. etc. etc. It enables those of similar interests to communicate and exchange views, observation pictures etc.

We are now inviting members of Guildford Astronomical Society to join us in this new exciting project, and who knows where it could lead. If you would like to join – and I

Telescopes for Loan No telescope? Still want to see planets and deep-sky objects? That’s not a problem if you’re a member. Take advantage of the Society’s loan scheme. To find out how it works and what you can choose, read on....

s we have had so many new members re- 2 – AstroSystems 6” F8, pillar, alt azimuth mount, A cently, it‟s probably time to remind all mem- undriven, (no photo available). bers that the Society has four telescopes that are available to loan. Quite often beginners to astronomy are uncertain about what sort of telescope to buy, and whether or not they‟d be able to use one; so this Society resource gives you an excellent opportunity to try one out. Loans are only available to paid up members, and are completely free, there‟s no deposit required. Up until now we haven‟t put a time limit on the loans, but we plan to operate on a three-month minimum period, renewable if there‟s no-one else waiting to borrow. Loans have been a bit sluggish of late, but I‟m hoping that we can keep these scopes in circulation by promoting their use a bit more strongly.

All four instruments are Newtonian reflecting telescopes: 3 – Tal 2 6” F8, pillar, equatorial mount, driven 1 - Celestron 4½” F9, tripod, equatorial mount, undriven

4 – Orion Optics 8” Europa F6, Dobsonian mount

5—Fullerscopes 10” Newtonian 1981 quality UK build. Excellent optics on Mark III Equatorial Mount - exceedingly solid! Misc. 1.25” Eyepieces, inc Barlow.

All of the telescopes are equipped with a finder- scope, and at least two eyepieces.

If you‟d like to borrow one then please register your interest with either John Axtell ([email protected]) or Tony Questa ([email protected]).

Let‟s keep these scopes in use!

Those of you who were at the March meeting and stayed until after the coffee break will remember that I promised to submit details of how to join the H.A.S servers list. We are inviting members of Guild- ford A.S to join this exciting new project, and who knows where it could lead?

So, to join the Houston A.S list, the members should send an email to: [email protected] You should get a message back in a few minutes that you are now subscribed. In the body of the message put:subscribe haslist

i.e. subscribe haslist Joe Bloggs Nothing is needed for the subject line. Do not sign e-mail

This is an excellent opportunity to exchange views and ideas with our fellow observers in Houston

Brian Gordon-States

Tour of the Night Sky

17th April is of course the date for our next Tour of The Night Sky at Newlands Corner. Julia's just about to go on hols and so she has asked me to look after this in her absence. At the meeting I'll be ask- ing for volunteers for some specific jobs on the night and trying to get an estimate about how many telescopes you'll all be bringing. Please by all means drop me an email so that when Julia gets back from holiday she'll see that it's well in hand. Don't forget, there's a flyer for the event that can be downloaded from our website. If you haven't already done so, please print this out and pop in shop win- dows, libraries, noticeboards, at work - wherever you think it will attract punters!

John Axtell

Training Courses

We have two quite separate and distinct sets of training on offer this month.

On Tuesday April 23rd we have the 3rd of our series of 4 introductory sessions, aimed primarily at newcomers to the hobby. This will look at some of the free astronomical software that can be a boon, together with an intro to sketching what we see at the eyepiece. If you've missed the previous two, but wish to attend, that's fine, these are stand-alone sessions. Just drop our Secretary, John Axtell ([email protected]) an email to let him know that you'd like to attend.

This is quite different to the Image Processing Training that John Evans will be running starting Tues- day, 9th April. This is a follow-on from the image acquisition training that many have done at the Holmbury Observatory. If you haven't done this essential precursor training, but feel that you already have equivalent experience, then it's best to contact John first - [email protected]

Page 14 © copyright 2010 guildford astronomical society www.guildfordas.org Latest on the New Observatory The latest work party was up at Holmbury St Mary on March 21st. See the latest pictures on how it’s shaping up. Words courtesy of John Evans

Chance leading proceedings and giving unstintingly of their time and expertise. Thanks all!

As you can see from the pics, the sliding roof is now in place. There are a few finish- ing touches to be made to the front 'flap' - required, you'll recall, to enable access to the southern horizon - after which we can clean-up inside and coat the floor. As soon as it's clean inside, it will be possible to set up the mount and polar align it and make some first light test images.

The permanent cabling can be laid after that.

Attached a few pics of what's happened today at Holmbury. Another

great effort, with, again, The Peters

The Night Sky in April

Note: The map shows the general appearance of the night sky at 11pm on the 15th April. The sky will look roughly the same at midnight on the 1st, and at 10pm at month-end.

The Night Sky in May

Note: The map shows the general appearance of the night sky at 11pm on the 15th May. The sky will look roughly the same at midnight on the 1st, and at 10pm at month-end. Data reproduced courtesy of the Federation of Astronomical Societies 2010 Astro Calendar, Cartes du Ciel.

What’s on - April/May

28th Apr st Full Last 6th Apr New 14th-Apr 1 18:20 21st-Apr Moon Qtr Qtr 27 May 6th May 14 May 20 May

Mercury reaches its greatest elongation on April 8, when it is the farthest it Mercury can get from the sun in our sky. Mercury shines at magnitude -0.9 at the beginning of the month and dims to -0.1 by midmonth when it disappears and rejoins the sun at sunset. In the first two weeks of April, look west as soon as the sun has set. Mercury can be found to the lower right of brilliant Venus. By April 8 they are nearly even in height from the horizon; after this date, Mercury begins to sink lower and dim until it can no longer be seen. April 3 & 4 Venus and Mercury at their closest, 3 degrees apart

Venus takes center stage as it is the brightest point of light in the sky after Venus sunset. At about magnitude -4, it is low in the west and sets about an hour and a half after the sun but is up for more than two hours by the end of the month. April 15 & 16 Thin crescent moon near Venus Mars is high overhead in the southwest. Mars lies in the constellation Can- Mars cer the Crab. On April 15, 16, and 17, Mars passes the star cluster known Planets as the Beehive Cluster, M44. Mars shines at magnitude 0.2 early in the month and has faded slightly to magnitude 0.7 by the end of April. at the start of the month it is visible low in the east in the morning twilight Jupiter shining brightly at magnitude -2.0. It is much the same throughout the month and into May. is visible all night as it is in opposition during April. It is in the constellation Saturn of Virgo and shines brightly at magnitude +0.6. It fades slightly during May but is still visible for most of the night. Uranus Both planets are morning stars but lost in the twilight as they are very faint. Neptune Whilst the determined observer may be able to locate them, the rest of us should wait until later in the year when the become very much easier to observe.

The Lyrid meteor shower occurs between April 19 and 24, with the peak of Phenomena Lyrid activity expected on April 22. Lyra rises in the northeast a couple hours af- Meteor ter sunset. Comet Thatcher is the parent body of the Lyrid meteor shower. Shower At its peak, an observer can expect about 12 meteors per hour, although the Moon will interfere this year.

Note: More details on specific events will be posted regularly on the Bulletin Board, http://forum.guildfordas.org/.

Page 19 © copyright 2010 guildford astronomical society www.guildfordas.org The Realm of the Galaxies April is perhaps the best month in the year to go on a tour of the Realm of the Galaxies. Peter Dean explains all, which is probably just as well.

The cloud of objects plotted on the chart above lying in the bowl of Virgo is the Virgo galaxy cluster, aka ‘The Realm of the Galaxies’.

ook south on any clear ies. Nowhere else in the sky is the spring evening and you‟ll concentration even remotely as high. find the constellations Leo On the boundary between Virgo and (The Lion) and Virgo, (the Coma Berenices is the enormous LVirgin). Both constellation are domi- Virgo Cluster. The Virgo Cluster is nated by a first first magnitude star, approximately 60 million +/- 10 mil- The brightest star in Leo is Regulus lion light-years distant. The Virgo and for Virgo it‟s Spica. Cluster has more than a thousand, crowded into a volume with a radius Between both constellations and around 5 million light years. Planets above the line between Spica and within galaxies at the heart of the Regulus lies the Realm of the Gal- Cluster have hundreds of galaxies axies. The only bright star in this easily visible to the unaided eye. area is Denebola, which marks ei- Studies show that the typical Virgo ther Leo‟s rear-end or the tip of the cluster galaxy is similar to our own. his tail, depending on which text you So other than the fact the cluster is read.. The title of Realm of the Gal- nearby, it is average as things go. axies only appears in a few texts, but it is fully justified. Hubble (yes, the same bloke as the telescope was named after) specu- In this area are thousands of galax- (Continued on page 21)

The northern section of the Virgo cluster, dominated by the trio of Messier objects, M87, M84 and M86. All the objects shown above can be observed with a 200mm telescope, and most of the brighter objects are visible in 80mmtele- scopes, or large binoculars (Continued from page 20) Nebulae and Star Clusters and start lated that it was possible to infer the at mag 5 Rho Virginis, the brightest history of a galaxy from its shape star of what would otherwise be a (spiral, irregular and elliptical). It is straight line of three brightish stars, thought that most galaxies start as the top of which is 27 Vir at mag 6. spirals. Irregular galaxies are created (in the above chart, rho Vir can be from close encounters between light found in the bottom left hand corner, and massive galaxies. Large galaxies if you follow the directions to ob- at the centre of a cluster accrete jects in the text, north is up and west smaller galaxies, growing to huge is right). These are the brightest stars sizes with an elliptical or spherical that we‟ll be encountering. Off to the shape. If you measure the mass, el- west, 41‟ away is NGC 4608, an liptical are preferentially more mas- 11th mag spiral, visible in larger ap- sive than any other galaxy shape, so ertures. From Rho, hop north it isn‟t suprising that the Virgo Clus- roughly 1.5 degrees and you‟ll find ter is dominated by elliptical galax- the first Messier object, M59 (mag ies. 9.6), with M60 (mag 8.8)just 25‟ away to the east. Both should appear In this tour, the route we‟ll follow is in the same low-power field. M59 similar to the one given by Kenneth was discovered by Johann Koehler Glyn Jones in his book, Messier's (Continued on page 22)

Page 21 © copyright 2010 guildford astronomical society www.guildfordas.org on April 11, 1779, together with nearby M60, on same low-power field. the occasion of observing the comet of that year. Charles Messier, also when observing that The next objects are rather fainter than what comet, found both galaxies four days later, on we‟ve been looking at so far, but are noteworthy April 15 of that year, and in addition nearby as they make up a set of object called Mark- M58 which Koehler missed. Messier described arian‟s Chain. The chain starts at M84/6 and M59 as equally faint as M58, and fainter than curves its way eastwards and northwards. From M60. Both objects are pretty uninteresting ellip- M84 hop 23‟ east to NGC4435/8, then 20‟ north tical, and representative of the sort of objects east to NGC 4461. Then by a similar amount that we‟ll be observing shortly. Midway be- north to NGC4473. 12‟ north is NGC 4477, then tween these two and slightly south is NGC 4638 25‟ northwest is NGC 4459. another moderately faint (mag 12.2) but otherwise unremarkable NGC object. If you have a Moving 50‟ northeast we arrive at a bright widefield eyepiece you may be able to see all Messier object, M88, (mag 9.6). This galaxy is three in the field. symmetrical has multiple spiral arms. Inclined by 30 degrees, it looks similar to M31, the An- From M59, sweep west 1 degree to arrive at dromeda galaxy. M58 (mag 9.7). On the way, look out for NGC 4606/7. These two galaxies are rather faint, so Moving swiftly on, hop 49‟ E and you should don‟t be surprised if you don‟t spot them. M58, find the much fainter galaxy M91 (mag 10.2). on the other hand is strikingly obvious, as it‟s This is another example of a barred spiral, has one of a handful of bright barred spirals in the an interesting history as it was one of Messiers cluster and is located to the SE of a triangle of „lost‟ objects, as it had been catalogued by him faint stars. with an incorrect position. Messier documented its position as an offset from M89, whilst under Now sweep 52‟ northwest to arrive at M89 (mag the impression that he was in fact using M58. 9.8), the first E0 galaxy of the evening. Looking The Texas amateur William C. Williams of Fort like a spherical fuzz ball, and nothing like M58, Worth sorted the confusion out fifty years ago. this is a massive object. M89 is one of Charles It had been thought that M91 had either been a Messier's own discoveries. He catalogued it on comet or a duplicate observation of M58. We‟re March 18, 1781, along with seven other discov- all done with M91, so now move 27‟ southeast eries in the Coma/Virgo region and the globular to arrive at NGC 4571. cluster in Hercules, M92. Now go south 1degree 5‟ to arrive at M90. M90 From M89, we make a big hop, 1 degree 12‟ (mag 9.5) is one of the larger spirals, and has west to arrive at the centre of the Virgo cluster tightly wounded, smooth bright spiral arms. If indicated by M87 (mag 8.7). At a diameter of 7', you feel lucky...well do ya? go 1 degree 45 min this implies a diameter of 120,000 light years, east to find a rather nice duo of galaxies: NGC more than the diameter of our Milky Way's disk. 4654 and the rather more challenging NGC As a E0/1 type elliptical it has much larger vol- 4639. Return back the way you came to M90, ume, and contains many times more stars (and and now go instead 40‟ south to arrive back at mass) than our galaxy. M87 is famous for two M89. peculiar features, a huge system of globular clusters surround it, and a spectacular jet of ma- From M89 go southeast 52‟ to arrive at M58, terial which is well seen on short exposure im- then 30‟ southwest to arrive at NGC4564. 11‟ ages. It indicates the existence of a supermassive away to the south is the duo of NGC4567 and black hole at the centre. NGC4568.

From there, jump 1 degree 15‟ west to the heart This short tour is now at an end and you can of the Virgo cluster; the trio of M86 (mag 8.9), breathe a sigh of relief...You‟ve probably seen M84 (mag 9.1) and NGC 4388 (mag 10.8) a more Messier objects in a single session than faintish edge-on spiral, all three visible in the you thought possible!